IRNA Iraq's Grand Cleric Ayatollah Ali Sistani said in a statement that US violated Iraqi national sovereignty by targeting Iranian commander Qasem Soleimani in Iraq, calling on all parties to exercise self-restraint.
In his statement, Ayatollah Sistani said that US brutal attacks led to assassination of a number of champions in fight against ISIS terrorists.
He added that the US aggression is vivid violation of Iraq's sovereignty and the UN Charter.
Lieutenant General Soleimani and the acting commander of the Iraqi Popular Mobilization Units (PMU) - known as the Hash al-Shaabi - Abu Mahdi Al-Mohandes, who were separately leaving Baghdad airport in two cars were targeted and assassinated.
Iraqi media said the US helicopters targeted both cars.
Earlier, Iran's Supreme Leader Ayatollah Seyyed Ali Khamenei commented on the martyrdom of the great commander of the IRGC's Quds Forces and said harsh and severe revenge is awaiting the criminals.